Although some cellular phone service providers will encrypt communications between a cellular phone and the base station (e.g., cell phone tower) with which the cellular phone is currently communicating, such providers generally decrypt such communications at the base station. Thus, such communications exist in unencrypted form at some point. Accordingly, such cellular phone service providers fail to provide for real-time voice communications between a mobile phone and another telephonic device that are encrypted throughout their entire passage between phones, i.e., such service providers fail to provide real-time end-to-end encryption of voice communications. (As used herein, the terms “end-to-end” and “end to end,” when used in conjunction with the terms “encrypt,” “encrypted” and so forth, mean that the communications are not in an unencrypted state at any point during their entire path between telephonic devices, except at the telephonic devices themselves.)
In general, prior art techniques for allowing mobile phones to provide end-to-end encryption of real-time voice communications require specially designed and manufactured cellular phones, cooperation from an associated service provider, or significant effort exerted by the conversing parties to coordinate the encrypted conversation (e.g., manually dialing multiple numbers or manually conveying cryptographic keys among the communicating parties). Thus, there is a need for an efficient technique that allows standard mobile phones to send and receive real-time voice calls that are encrypted from end to end without requiring special cooperation from communication service providers.